Heretofore, various containers for sealing food have been proposed. For example, JP 2004-113776A discloses a container that includes a container body having an opening in the upper part and a lid attached to the container body for sealing. The lid of this container is provided with a swingable flap, and the container is configured to be capable of opening or closing the air hole formed in the lid by the flap. More specifically, the projection provided on the lower surface of the flap is fitted in the air hole to attain an airtight state, and the flap is lifted upright to remove the projection from the air hole, thus making it possible to introduce air into the container. Accordingly, closing the air hole by the flap makes it possible to seal the container, and on the other hand, operating the flap to open the air hole makes it possible to, for example, suitably release the steam inside the container through the air hole when heating food in a microwave oven. In this container, a circular gasket is attached to the projection to enhance the adhesion between the projection and the air hole.
Meanwhile, attachment of a circular gasket to the projection as described above is problematic in that it results in an increased number of components although the adhesion between the projection and the air hole is enhanced. In addition, it is also problematic in that the container cannot be sealed if the gasket is detached and lost. Accordingly, it is possible to consider fitting the projection in the air hole without using a gasket. However, it is not easy to precisely adhere the projection to the air hole if the flap and the lid are integrally formed. For example, if adhesion is poor, not only can the container not be sealed but also the projection may be easily detached from the air hole. Such problems are applicable to not only food containers but also containers in general that need to be brought into an airtight state and an aerated state.
Accordingly, the present invention has been conceived in view of the foregoing problems, and an object of the present invention is to provide a lid that can secure adhesion between the projection and the air hole even when the flap is integrally formed, and a container provided with the lid.